Geology articles within Nature

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  • Obituary |

    Seismologist who helped demonstrate that Earth's continents move constantly.

    • Peter Molnar

  • News & Views |

    Sediments at the edge of Antarctica are a largely unexploited source of information about climate change. They have now provided a valuable local record of sea surface temperatures for the past 12,000 years. See Letter p.250

    • James Bendle

  • News & Views Forum |

    Many scientists now use the power of computer models to advance their subjects. But there is a choice: to simplify complex systems or to include more detail. Modelling the intricate processes of sedimentary geology is a case in point.

    • Chris Paola
    •  & Mike Leeder

  • Letter |

    The unusual capability of solid crystalline materials to deform plastically (known as superplasticity) has been found in metals and even ceramics; however, no experimental studies have yet to demonstrate this behaviour in geological materials. It is now demonstrated that some synthetic rocks, which are good analogues for Earth's mantle, undergo homogeneous elongation up to 500% under subsolidus conditions. Calculations show that such superplastic flow in the mantle is inevitably accompanied by significant grain growth that can change fine-grained rocks to coarse-grained aggregates, resulting in increasing mantle viscosity and finally termination of superplastic flow.

    • Takehiko Hiraga
    • , Tomonori Miyazaki
    •  & Hidehiro Yoshida

  • Letter |

    Here, an indirect estimate for the magnetic field strength within the Earth's core from measurements of tidal dissipation is presented. Previously reported evidence of anomalous dissipation in the Earth's nutations can be explained with a core-averaged field of 2.5 mT, eliminating the need for high fluid viscosity or a stronger magnetic field at the inner-core boundary.

    • Bruce A. Buffett

  • Brief Communications Arising |

    • T. L. Grove
    • , C. B. Till
    •  & E. Médard

  • Comment |

    New forecasts suggest that coal reserves will run out faster than many believe. Energy policies relying on cheap coal have no future, say Richard Heinberg and David Fridley.

    • Richard Heinberg
    •  & David Fridley

  • Letter |

    The deformation style at moderately active volcanoes — such as Eyjafjallajökull, Iceland, which underwent an explosive summit eruption earlier this year — is little understood. These authors show that deformation associated with the eruptions at Eyjafjallajökull was unusual as it did not relate to pressure changes within a single magma chamber, and infer that this behaviour might be attributed to its off-rift setting with a 'cold' subsurface structure and limited magma at shallow depth.

    • Freysteinn Sigmundsson
    • , Sigrún Hreinsdóttir
    •  & Kurt L. Feigl

  • Letter |

    These authors use seismic imaging to accurately measure fault extension at the conjugate west Iberia and Newfoundland margins and compare this with crustal thinning. They use these observations to create a balanced kinematic model of rifting that resolves the extension discrepancy — where crustal thinning seems to be greater than the extension caused by brittle faulting.

    • César R. Ranero
    •  & Marta Pérez-Gussinyé

  • News & Views |

    Evidence of intense phosphorus weathering following 'snowball Earth' glaciations raises a further possibility — that this revved-up nutrient cycle drove conditions for the explosion of animal life. See Letter p.1088

    • Gabriel M. Filippelli

  • Letter |

    The Palaeocene–Eocene thermal maximum (PETM) is a well-known abrupt warming that occurred at about 55.8 Myr ago and is usually thought to have been caused by a large release of greenhouse gases, as recorded in a large carbon isotope excursion. Yet some marine evidence suggests that in fact the warming came first. Here it is shown that continental warming of about 5 °C preceded the excursion in the Bighorn Basin, Wyoming. Thus the PETM seems to have been caused by at least two separate warming events.

    • Ross Secord
    • , Philip D. Gingerich
    •  & Kenneth G. MacLeod

  • Letter |

    These authors use a scaling argument derived from a model of heat transfer in subduction zones to argue that the locations of volcanic arcs cannot be explained by the release of fluids in reactions taking place near the top of the slab. Instead, they conclude that the sharpness of the volcanic fronts, together with the systematics of their locations, require that arcs be located above the place where the boundary defined by the anhydrous solidus makes its closest approach to the trench.

    • Philip C. England
    •  & Richard F. Katz

  • Letter |

    These authors test whether patterns of seismicity and the stabilities of potentially relevant hydrous phases are consistent with a wet lithosphere. They show that there is nearly a one-to-one correlation between the dehydration of minerals and seismicity at depths less than ∼250 km, but no correlation at greater depths. They conclude that subducting slabs must be essentially dry by 400-km depth and thus do not provide a pathway for significant amounts of water to enter the mantle transition zone or the lower mantle.

    • Harry W. Green II
    • , Wang-Ping Chen
    •  & Michael R. Brudzinski

  • Letter |

    Water within glaciers and ice sheets has a strong potential to influence ice velocity and, ultimately, the rate of sea-level rise. But so far direct measurement of the magnitude and characteristics of water stored within glaciers has proved difficult. Here, a combination of in situ borehole measurements and radar and seismic imaging has been used to show that there is an extensive network of basal crevasses in the Bench Glacier in Alaska. The crevasses hold water equivalent to at least a decimetre layer.

    • Joel T. Harper
    • , John H. Bradford
    •  & Toby W. Meierbachtol

  • Letter |

    Earthquake instability has long been attributed to fault weakening during accelerated slip, but what are the mechanisms that control this weakening? Here laboratory evidence is presented for the dynamic weakening of faults that are sheared at velocities approaching earthquake slip rates. The experimental faults, made from solid granite blocks, quickly wore to form a fine-grain rock powder, known as gouge, which reduced the faults' strength. It is concluded that only newly formed gouge can weaken the experimental faults.

    • Ze’ev Reches
    •  & David A. Lockner

  • Letter |

    It has been suggested that glacial erosion has an important role in controlling mountain height. Here, spatial and temporal patterns of erosion in the glaciated Patagonian Andes have been assessed with the help of a low-temperature thermochronologic data set. The results show that, between 38° S and 49° S, accelerated erosion at the onset of widespread glaciation limits mountain height. But at higher latitudes, glaciation protects the landscape from erosion and leads to growth in mountain height and width.

    • Stuart N. Thomson
    • , Mark T. Brandon
    •  & Nathaniel J. Wilson

  • News & Views |

    Glaciers frozen to bedrock may have protected the southernmost Andes from erosion, providing an explanation for the mountains' topography and fresh constraints on possible links between climate and tectonics.

    • Jean Braun

  • Letter |

    The Younger Dryas — during which Northern Hemisphere temperatures cooled drastically in just a few years — is perhaps the best-known example of abrupt climate change, but its global extent is under debate, particularly in the record of glacial behaviour in New Zealand. These authors present evidence for glacial retreat in New Zealand during the Younger Dryas, supporting the hypothesis that Northern Hemisphere climate changes caused Southern Hemisphere warming through a series of climate feedbacks.

    • Michael R. Kaplan
    • , Joerg M. Schaefer
    •  & Alice M. Doughty

  • Letter |

    These authors show evidence for a high coherence between the slip distribution inferred from the 2010 Maule earthquake, Chile, and the patchwork of interseismic locking distribution derived from global positioning system observations during the previous decade. Their work suggests that coseismic slip heterogeneity at the scale of single asperities should indicate the seismic potential of future earthquakes, which thus might be anticipated by geodetic observations.

    • Marcos Moreno
    • , Matthias Rosenau
    •  & Onno Oncken

  • News & Views |

    Meticulous reconstruction of the former extent of a glacier high in the mountains of New Zealand will help in interpreting global-scale climatic adjustments that occurred at the end of the last glaciation.

    • Martin P. Kirkbride

  • News Feature |

    A project to drill a 10-kilometre-deep hole in China will provide the best view yet of the turbulent Cretaceous period. Jane Qiu reports.

    • Jane Qiu

  • Letter |

    Cratons, the ancient cores of continents, extend laterally for hundreds of kilometres, and are underlain to depths of 180–250 km by mantle roots that are chemically and physically distinct from surrounding mantle. But how can these roots stay so isolated from mantle convection? Here it is shown that olivine in peridotite xenoliths from the lithosphere–athenosphere boundary region of the Kaapvaal craton mantle root is water-poor, providing sufficient viscosity contrast with the underlying asthenosphere to explain the root's stability.

    • Anne H. Peslier
    • , Alan B. Woodland
    •  & Marina Lazarov

  • Letter |

    At the end of the last ice age, rising atmospheric CO2 levels coincided with a decline in radiocarbon activity, suggesting the release of highly radiocarbon-depleted CO2 from the deep ocean to the atmosphere. These authors present radiocarbon records of surface and intermediate-depth waters from two sediment cores and find an decrease in radiocarbon activity that precedes and roughly equals in magnitude the decrease in the atmospheric radiocarbon signal during the early stages of the glacial–interglacial climatic transition.

    • Kathryn A. Rose
    • , Elisabeth L. Sikes
    •  & Howard J. Spero

  • Article |

    These authors show that changes in seismic anisotropy with depth across the stable part of North America reveal the presence of two lithospheric layers. The top layer, which is chemically depleted, is ∼150 km thick under the ancient core of the continent and tapers out along its younger borders. The bottom of the lithosphere is relatively flat, in agreement with the presence of a thermal conductive root that subsequently formed around the depleted chemical layer.

    • Huaiyu Yuan
    •  & Barbara Romanowicz

  • Letter |

    On 29 September 2009, a tsunami devastated the Samoan and northern Tongan islands. Here, an unusual earthquake sequence that preceded this tsunami is analysed. A magnitude-8.1 intraplate faulting event in the outer trench-slope at the northern end of the Tongan subduction zone was followed by extensive interplate faulting, with total moment equivalent to that of a magnitude-8.0 earthquake. Overlap of the seismic signals had obscured the fact that distinct faults had ruptured with different geometries.

    • Thorne Lay
    • , Charles J. Ammon
    •  & Alexander R. Hutko

  • Letter |

    On 29 September 2009, a tsunami devastated the Samoan and northern Tongan islands. It is shown here that an unusual earthquake sequence preceded this tsunami. A magnitude-8 earthquake in the outer-rise intraplate region occurred almost simultaneously with rupture of the shallow subduction interplate interface, equivalent to a magnitude-8 earthquake. The findings provide information on strain release mechanisms at subduction zones, and a possible mechanism for the occasional large tsunamis generated at the Tonga subduction zone.

    • J. Beavan
    • , X. Wang
    •  & R. Kautoke

  • News & Views |

    A puzzling case is presented by the occurrence of two large but dissimilar earthquakes at almost the same time and place. One must have acted as the trigger, but which one and how did it do so?

    • Kenji Satake

  • Letter |

    Cloud simulation is one of the most challenging tasks in regional to global-scale modelling. In many cases, the physical mechanisms responsible for observed cloud dynamics are unknown, making it difficult to realistically simulate their structure and behaviour. These authors show that open cellular clouds — characterized by low albedo — can be created by precipitation-driven downdrafts and that the resulting cloud structure forms an oscillating, self-organizing cloud field.

    • Graham Feingold
    • , Ilan Koren
    •  & Wm. Alan Brewer

  • Letter |

    High 3He/4He ratios in some basalts have been interpreted as evidence for ancient reservoirs preserved in the Earth’s mantle; however, such rocks have never been observed to host the primitive lead-isotopic compositions required for an early formation age. These authors show that Baffin Island and West Greenland lavas exhibit primitive lead-isotope ratios consistent with a mantle source age of 4.55–4.45 billion years, and that their source may be the most ancient accessible reservoir in the mantle.

    • Matthew G. Jackson
    • , Richard W. Carlson
    •  & Jerzy Blusztajn

  • News |

    Geological storage of long-lived radioactive material is moving closer to reality in Europe, says Declan Butler.

    • Declan Butler

  • Letter |

    These authors show that simultaneous crystallization and melting at the surface of the Earth's inner core can result in a translational mode of thermal convection within the inner core, producing the observed stratified layer of reduced seismic velocity at the base of the outer core. The dynamical model they propose also introduces an asymmetry between hemispheres that may explain the enigmatic East–West asymmetry in seismic properties of the inner core.

    • Thierry Alboussière
    • , Renaud Deguen
    •  & Mickaël Melzani

  • Letter |

    These authors argue that the concentration of magnitude-7 or larger earthquakes in the New Madrid seismic zone since the end of the last ice age results from the recent, climate-controlled, erosional history of the northern Mississippi embayment. They show that the upward flexure of the lithosphere caused a reduction of normal stresses in the upper crust sufficient to unclamp pre-existing faults close to failure equilibrium.

    • E. Calais
    • , A. M. Freed
    •  & S. Stein

  • Letter |

    These authors report the concentrations of hydrogen, chlorine and sulphur in the mineral apatite from a lunar basalt, and show that the concentrations are indistinguishable from apatites in common terrestrial igneous rocks. They conclude that both metamorphic and igneous models of apatite formation suggest a volatile inventory for at least some lunar materials that is similar to comparable materials within the Earth.

    • Jeremy W. Boyce
    • , Yang Liu
    •  & Lawrence A. Taylor

  • Letter |

    Deep seismic tremor in subduction zones has been suggested to repeat at a regular interval, migrate at various velocities and be modulated by tidal stress. Here, evidence is presented that a time-invariant interface property — possibly the ratio of brittle to ductile areas — controls tremor behaviour in the Nankai subduction zone, Japan. Where tremor duration is short, tremor is more strongly affected by tidal stress and migration is inhibited. Where tremor lasts longer, diffusive migration occurs with a constant diffusivity.

    • Satoshi Ide

  • Letter |

    Diamonds are formed under high pressure more than 150 kilometres deep in the Earth's mantle, and are brought to the surface mainly by volcanic rocks called kimberlites. Here, plate reconstructions and tomographic images have been used to show that the edges of the largest heterogeneities in the deepest mantle, stable for at least 200 million years and possibly for 540 million years, seem to have controlled the eruption of most Phanerozoic kimberlites. This has implications for future exploration for kimberlites.

    • Trond H. Torsvik
    • , Kevin Burke
    •  & Lewis D. Ashwal

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